How to upadate my Macbook Air (Early 2015) model to IOS 10.15?
How to upadate my Macbook Air (Early 2015) model to IOS 10.15?
MacBook Air 13″, OS X 10.11
You can download macOS 10.15 Catalina from the Mac App Store. If macOS Catalina doesn't appear in the Mac App Store, you can download the installer directly from Apple Support at this website using Safari.
How to get old versions of macOS - Apple Support
Your device is also compatible with macOS 12 Monterey. For more features and better security, you should install macOS Monterey.